1. Field of the Invention
The present invention relates to an improved actuating apparatus for inflating a vehicle occupant protection system employing an airbag.
2. Description of the Prior Art
In recent years vehicle occupant protection systems employing inflatable, cushioning airbags have been adopted by vehicle manufacturers as a means for minimizing the extent of death and injury that occurs in highway vehicles that are involved in collisions. It has become increasingly evident that the use of airbags in automotive vehicles saves many vehicle occupants from death and reduces the extent of injury of vehicle occupants involved in collisions. Therefore, more and more newer models of automotive vehicles are being equipped with manufacturer installed vehicle airbags. However, due to the expense involved, conventional vehicle airbag systems are typically provided by manufacturers only at the driver position, or at the most at the driver position and at the position of a front seat occupant of a vehicle.
A conventional occupant protection system employing an airbag involves the provision of an initially collapsed bag of air impervious material such as plastic or rubber, concealed behind a dashboard panel or positioned at the top of the steering wheel column. When a vehicle is subjected to an impact, particularly along the direction of alignment of the vehicle, a shock or inertia sensitive actuator opens a valve that admits compressed air from a compressed air reservoir into the occupant protection airbag. Alternatively, pyrotechnic actuators may be employed to inflate the airbag. With either arrangement the airbag rapidly inflates so that the occupant of a vehicle seat is pressed back into the seat, and is not thrown forward through the windshield or into the vehicle dashboard. Inflation of the airbag occurs within a split second of impact against the vehicle, since the airbag must be rapidly inflated in order to provide a cushioning effect to the vehicle occupant. Conventional airbags are equipped with pressure relief systems that quickly deflate the airbag shortly after the impact, so that a vehicle occupant is not trapped within a vehicle once the vehicle has come to rest.
Conventional vehicle airbag inflation systems employ inordinately complex crash detection mechanisms or electronic sensors. As a result, the types of actuation systems currently employed to control the inflation of occupant protection airbags in a vehicle do not lend themselves to installation in a vehicle once the manufacture of the vehicle has been completed. This is particularly unfortunate, since for many years vehicles were not provided with occupant protection airbags and most of the vehicles on the road today lack these valuable occupant protection devices. Furthermore, even new vehicles which are currently being manufactured are typically provided with protective airbags only at the driver position. While an optional airbag can be installed in front of a front seat passenger position, occupants of rear seats in a vehicle are left totally without the protection of an inflatable airbag.
The current design of conventional automotive occupant protection systems do not permit easy installation of such systems in a vehicle once the vehicle has been manufactured. The actuating components of a vehicle airbag are typically located under the hood or within the body of a vehicle. Consequently, these actuating systems are not easily accessible for retroactive installation of airbags on a vehicle. Furthermore, the designs of conventional airbag actuation systems do not permit additional airbags to be operated by an existing inflation actuating arrangement. Thus, it is not practical to add conventional airbag protection systems to occupant seating positions lacking such devices.